for Journals by Title or ISSN
for Articles by Keywords
help
  Subjects -> ENGINEERING (Total: 2166 journals)
    - CHEMICAL ENGINEERING (185 journals)
    - CIVIL ENGINEERING (168 journals)
    - ELECTRICAL ENGINEERING (93 journals)
    - ENGINEERING (1171 journals)
    - ENGINEERING MECHANICS AND MATERIALS (356 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (57 journals)
    - MECHANICAL ENGINEERING (81 journals)

ENGINEERING (1171 journals)            First | 5 6 7 8 9 10 11 12 | Last

Journal of Visualization     Hybrid Journal   (Followers: 2)
Journal of Volcanology and Seismology     Hybrid Journal   (Followers: 3)
Journal of Wuhan University of Technology-Mater. Sci. Ed.     Hybrid Journal  
Journal of Zhejiang University SCIENCE A     Hybrid Journal  
Journal on Chain and Network Science     Full-text available via subscription   (Followers: 3)
Jurnal Teknik ITS     Open Access  
Jurnal Teknologi     Open Access   (Followers: 2)
Karaelmas Science and Engineering Journal     Open Access  
Kerntechnik     Full-text available via subscription  
Kleio     Full-text available via subscription   (Followers: 2)
Landscape and Ecological Engineering     Hybrid Journal   (Followers: 3)
Langmuir     Full-text available via subscription   (Followers: 42)
Latin American Journal of Computing     Open Access  
Leadership and Management in Engineering     Full-text available via subscription   (Followers: 10)
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Lighting Research and Technology     Hybrid Journal  
Logic and Analysis     Hybrid Journal  
Logica Universalis     Hybrid Journal  
Lubrication Science     Hybrid Journal  
Machines     Open Access   (Followers: 2)
Machining Science and Technology: An International Journal     Hybrid Journal   (Followers: 3)
Macromolecular Reaction Engineering     Hybrid Journal  
Magazine of Concrete Research     Hybrid Journal   (Followers: 7)
Magdeburger Journal zur Sicherheitsforschung     Open Access  
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 4)
Management and Production Engineering Review     Open Access  
Manufacturing Engineer     Hybrid Journal   (Followers: 3)
Manufacturing Research and Technology     Full-text available via subscription   (Followers: 3)
Marine Technology Society Journal     Full-text available via subscription  
MATEC Web of Conferences     Open Access  
Matériaux & Techniques     Full-text available via subscription   (Followers: 2)
Mathematical Models and Methods in Applied Sciences     Hybrid Journal   (Followers: 2)
Mathematical Problems in Engineering     Open Access   (Followers: 3)
Mathematics of Control, Signals, and Systems (MCSS)     Hybrid Journal   (Followers: 5)
Mauerwerk     Hybrid Journal  
Measurement     Hybrid Journal   (Followers: 2)
Measurement Science Review     Open Access   (Followers: 1)
Meccanica     Hybrid Journal   (Followers: 1)
Mechatronics     Hybrid Journal   (Followers: 4)
Medical and Biological Engineering and Computing     Hybrid Journal   (Followers: 2)
Medical Engineering & Physics     Hybrid Journal   (Followers: 9)
Membrane Science and Technology     Full-text available via subscription   (Followers: 2)
Membrane Technology     Full-text available via subscription   (Followers: 2)
Memetic Computing     Hybrid Journal  
Metabolic Engineering Communications     Open Access  
Metal Powder Report     Full-text available via subscription   (Followers: 4)
Metallurgist     Hybrid Journal   (Followers: 3)
Metaphysica     Hybrid Journal   (Followers: 1)
Metascience     Hybrid Journal   (Followers: 1)
Metrologia     Full-text available via subscription   (Followers: 1)
Microelectronic Engineering     Hybrid Journal   (Followers: 5)
Microelectronics International     Hybrid Journal  
Microelectronics Journal     Hybrid Journal   (Followers: 6)
Microelectronics Reliability     Hybrid Journal   (Followers: 8)
Microfluidics and Nanofluidics     Hybrid Journal   (Followers: 10)
Micromachines     Open Access   (Followers: 3)
MNASSA : Monthly Notes of the Astronomical Society of South Africa     Full-text available via subscription  
Modelling and Simulation in Engineering     Open Access   (Followers: 4)
Modern Applied Science     Open Access   (Followers: 1)
Molecular BioSystems     Full-text available via subscription   (Followers: 5)
Molecular Engineering     Hybrid Journal  
Molecular Pharmaceutics     Full-text available via subscription   (Followers: 12)
MRS Bulletin     Full-text available via subscription   (Followers: 5)
MRS Online Proceedings     Full-text available via subscription   (Followers: 1)
Multidimensional Systems and Signal Processing     Hybrid Journal  
NANO     Hybrid Journal   (Followers: 8)
Nano Letters     Full-text available via subscription   (Followers: 52)
Nano Research     Hybrid Journal   (Followers: 4)
Nano Reviews     Open Access   (Followers: 15)
Nanopages     Full-text available via subscription   (Followers: 1)
Nanoscale and Microscale Thermophysical Engineering     Hybrid Journal   (Followers: 3)
Nanoscale Systems : Mathematical Modeling, Theory and Applications     Open Access  
Nanoscience and Nanoengineering     Open Access  
Nanoscience and Nanotechnology     Open Access   (Followers: 1)
Nanoscience and Nanotechnology Research     Open Access   (Followers: 1)
Nanotechnologies in Russia     Hybrid Journal   (Followers: 1)
Nanotechnology     Hybrid Journal   (Followers: 9)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 18)
Nanotechnology Reviews     Hybrid Journal   (Followers: 4)
Natural Hazards     Hybrid Journal   (Followers: 116)
Nature Nanotechnology     Full-text available via subscription   (Followers: 50)
Naval Engineers Journal     Hybrid Journal   (Followers: 2)
NDT & E International     Hybrid Journal   (Followers: 17)
Nexo Revista Científica     Open Access  
Nigerian Journal of Basic and Applied Sciences     Open Access   (Followers: 2)
Nigerian Journal of Technological Research     Full-text available via subscription  
Nigerian Journal of Technology     Full-text available via subscription  
NIR news     Full-text available via subscription  
Noise Mapping     Open Access  
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
Nonlinear Engineering : Modeling and Application     Hybrid Journal   (Followers: 1)
Nonlinearity     Full-text available via subscription   (Followers: 2)
Nordic Journal of Science and Technology     Open Access  
Nova Scientia     Open Access  
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 4)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 10)
Nuclear Engineering and Technology     Open Access  
Numerical Algorithms     Hybrid Journal  
Numerical Heat Transfer, Part A: Applications: An International Journal of Computation and Methodology     Hybrid Journal   (Followers: 5)
Numerical Heat Transfer, Part B: Fundamentals: An International Journal of Computation and Methodology     Hybrid Journal   (Followers: 7)

  First | 5 6 7 8 9 10 11 12 | Last

Journal Cover   Reactive and Functional Polymers
  [SJR: 0.879]   [H-I: 62]   [5 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1381-5148
   Published by Elsevier Homepage  [2812 journals]
  • Synthesis, functionalization and characterization of UV-curable lactic
           acid based oligomers to be used as surgical adhesives
    • Abstract: Publication date: Available online 21 July 2015
      Source:Reactive and Functional Polymers
      Author(s): J.M.C. Santos, D.S. Marques, P. Alves, T.R. Correia, I.J. Correia, Cristina M.S.G. Baptista, P. Ferreira
      The synthesis, functionalization and characterization of low molecular weight L-lactic acid based oligomers to be used as new UV-curable bioadhesives are presented herein. Prepolymers hydroxyl terminated were produced by L-lactic acid dehydration with 1,4-butanediol. The prepolymer was further modified with photoreactive sites by adding an isocyanate-functional unsaturated acrylic ester, which was used for the first time in the biomedical field (LAROMER® LR 9000). Films were afterwards produced upon UV irradiation for 120s, using a biocompatible photoinitiator (Irgacure® 2959), and finally characterized. The synthesized films exhibited a moderate swelling ratio, suitable for the envisioned application. DSC analysis confirmed an increase in Tg values after each synthesis step. Nevertheless, the film Tg remains lower than the physiological and room temperature. TGA confirmed an improved stability of films at high temperatures. The in vitro degradation tests showed their susceptibility to hydrolysis at 37°C, suitable for short-term uses. Preliminary evaluation of the adhesion capacity suggested that the synthesized material may be effective in sustaining wound closure and repair. The surface energy was also measured and its value was lower than the ones from blood or skin which supports the previous statement. Blood compatibility studies, cell viability assays (using human dermal fibroblasts) and bacterial inhibition tests (using two bacteria models) were performed. The results indicated that cured adhesive is bio/haemocompatible and possesses antimicrobial activity. Altogether, characterization results showed that the produced material presented a set of properties suitable for biomedical applications, particularly as a surgical adhesive.


      PubDate: 2015-07-24T21:41:24Z
       
  • Ring-opening reactions of backbone epoxidized polyoxanorbornene
    • Abstract: Publication date: Available online 17 July 2015
      Source:Reactive and Functional Polymers
      Author(s): Ufuk Saim Gunay, Erhan Demirel, Gurkan Hizal, Umit Tunca, Hakan Durmaz
      In this article, we report the synthesis of poly(oxanorbornene imide) (PONB) with internal epoxy groups (epoxidized-PONB30) and its ring-opening reactions with various nucleophiles, such as amine, azide, and thiols. The ring-opening reactions with amines yielded the amine-hydroxyl PONBs in the range of 36–95% of functionalization depending upon the amine content per epoxy. An allylamine-hydroxyl functionalized PONB was further functionalized efficiently with 1-octanethiol by radical thiol-ene reaction. The ring-opening reaction of the main chain epoxy using thiols resulted in a lower functionalization than amines with a similar functional group (e.g., allyl). In addition, sodium azide together with NH4Cl, was employed efficiently in the ring-opening reaction of the main chain epoxy, resulting in an azide/hydroxyl-functional PONB30 with 53% efficiency, which was determined after a model copper-catalyzed azide-alkyne cycloaddition (CuAAC) experiment was carried out.


      PubDate: 2015-07-20T21:39:34Z
       
  • Experimental design approach in the synthesis of molecularly imprinted
           polymers specific for iprodione fungicide
    • Abstract: Publication date: September 2015
      Source:Reactive and Functional Polymers, Volume 94
      Author(s): Manal Bitar, Jacqueline Maalouly, Hanna Chebib, Adrien Lerbret, Philippe Cayot, Elias Bou-Maroun
      An experimental design (ED) approach was applied to study the weight of three factors in the synthesis of a molecularly imprinted polymer (MIP) specific for iprodione fungicide. The objective was to obtain a high specific polymer with the best performance of iprodione binding. Thirteen iprodione-imprinted polymers and 13 non-imprinted polymers (NIP) were synthesized according to ED having 3 influencing factors: the polymerization method, the crosslinker nature and the functional monomer type. For each factor, two levels were studied: bulk and precipitation polymerization for the first factor, trimethylolpropane trimethacrylate (TRIM) and ethylene glycol dimethacrylate (EGDMA) for the second factor, and methacrylamide (MAM) alone or with styrene for the third factor. The ED responses were: the imprinting factor, the site number and the apparent affinity constant. They were determined after studying the interactions between iprodione and each MIP and NIP in hydro-alcoholic medium. The best polymer of the ED was synthesized using MAM as functional monomer, EGDMA as crosslinker and precipitation polymerization. It has an imprinting factor of 2.4, a site number of 1172 and an affinity constant of 19.36. The best MIP was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Nitrogen sorption isotherms. The best MIP has a mesoporous structure with a high specific surface area of 407m2·g−1. Molecularly imprinted solid phase extraction (MISPE) was successfully applied, using the best MIP, to preconcentrate iprodione from a white wine containing two competing fungicides.
      Graphical abstract image

      PubDate: 2015-07-16T21:28:29Z
       
  • Designing Packaging Materials with Viscoelastic and Gas Barrier Properties
           by Optimized Processing of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)
           with Lignin
    • Abstract: Publication date: Available online 7 July 2015
      Source:Reactive and Functional Polymers
      Author(s): Adriana Kovalcik , Michal Machovsky , Zuzana Kozakova , Martin Koller
      Microbial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) bio-polyester was combined by thermoforming with Kraft lignin in order to design new advanced composite materials for packaging purpose. After assessing the compatibility of the two raw materials, the thermoformed composite sheets were investigated in order to assess the impact of the lignin fraction (between 0 and 10 wt. %) on melting and crystallization behavior, thermo-oxidative stability, mechanical and viscoelastic properties, and permeability for oxygen and carbon dioxide. It turned out that the applied Kraft lignin is highly compatible with microbial PHBHV, and by exerting a reinforcing effect, acts as an active additive. As aspired, the gas permeability was decreased by combining PHBHV with 1 wt. % lignin; here, a reduction of permeability for oxygen by 77 % and by 91 % for carbon dioxide, respectively, was observed if compared to the native bio-polyester specimens. Also the low thermo-oxidation stability, a typical characteristic of pure PHBHV, was increased for the lignin-containing materials. This first report on thermoformed composite materials of microbial PHBHV and lignin suggests a new class of bio-based polymer materials to be applied for packaging of various easily perishable goods.


      PubDate: 2015-07-11T16:07:17Z
       
  • Synthesis of novel temperature responsive PEG-b-[PCL
           -g-P(MEO2MA-co-OEGMA)]-b-PEG (tBG) triblock-graft copolymers and
           
    • Abstract: Publication date: Available online 4 July 2015
      Source:Reactive and Functional Polymers
      Author(s): Yue-Ming An , Teng Liu , Rong Tian , Shou-Xin Liu , Ya-Nan Han , Qin-Qin Wang , Wei-Juan Sheng
      Novel triblock-graft copolymers, poly ethylene glycol-b-[poly(ε-caprolactone)-g- poly(2-(2-methoxyethoxy) ethyl methacrylate-co-oligo (ethylene glycol) methacrylate)]-b-poly ethylene glycol (PEG-b-[PCL-g-P(MEO2MA-co-OEGMA)] -b-PEG) (tBG), were synthesized via ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). In the synthesis process, temperature responsive P(MEO2MA-co-OEGMA) chains were grafted onto the PCL block of triblock copolymer PEG-b-PCL-b-PEG to improve its hydrophilicity. This method succeeded in increasing the solubility of PEG-b-PCL-b-PEG in water, and more importantly, endowing PEG-b-PCL-b-PEG with temperature sensitivity. By adjusting the feed ratio of 2-(2-methoxy ethoxy) ethyl methacrylate (MEO2MA) and oligo (ethylene glycol) methacrylate (OEGMA) monomers, the lower critical solution temperature (LCST) of the tBG can be realized at about 37°C. Taking advantage of the excellent mechanical property of graphene sheets, alkyne-functionalized graphene oxide (alkyne-GO) was introduced to cross-link tBGs and prepare tBG/GO composite hydrogel through click reaction between tBG-N3 and alkyne-GO. Different from traditional cross-linker, alkyne-GO acts as reinforcing fillers in the composite hydrogel. Benefited from superior properties of PCL, PEG, P(MEO2MA-co-OEGMA) and GO, the as-prepared temperature responsive tBG/GO hydrogel exhibits excellent mechanical strength and toughness, demonstrating a future potential applications in tissue engineering and biotechnology fields.


      PubDate: 2015-07-05T15:51:57Z
       
  • Synthesis of Sulfur-Containing Alternating Copolymers by RAFT
           Copolymerization of Phenyl Vinyl Sulfides
    • Abstract: Publication date: Available online 2 July 2015
      Source:Reactive and Functional Polymers
      Author(s): Yohei Abiko , Aiko Matsumura , Kazuhiro Nakabayashi , Hideharu Mori
      An electron-donating S-vinyl monomer, phenyl vinyl sulfide (PVS), was copolymerized with electron-accepting monomers, such as maleic anhydride (MA), N-methyl maleimide (MMI), and N-phenyl maleimide (PMI), via a reversible addition–fragmentation chain transfer (RAFT) process. Among various chain transfer agents (CTAs), the trithiocarbonate-type CTA was found to be effective in achieving controlled copolymerizations of PVS with the electron-accepting monomers with a strong alternating tendency. The controlled nature of the RAFT copolymerization of PVS with PMI was confirmed by the formation of narrow polydispersity products, with the molecular weight being controlled by the monomer/CTA molar ratio, resulting in an observed linear increase in the molecular weight with the polymer yield. RAFT copolymerization of PVS with an asymmetrical divinyl monomer, N-vinyl maleimide, in the presence of the trithiocarbonate-type CTA allowed the synthesis of alternating copolymer with pendant double bonds, which were available for subsequent thiol-ene click reaction to produce novel sulfur-containing copolymers.


      PubDate: 2015-07-05T15:51:57Z
       
  • Polymer-lipid interactions: biomimetic self-assembly behaviour and surface
           properties of poly(styrene-alt-maleic acid) with
           diacylphosphatidylcholines
    • Abstract: Publication date: Available online 3 July 2015
      Source:Reactive and Functional Polymers
      Author(s): Virginia Saez-Martinez , Patchara Punyamoonwongsa , Brian J. Tighe
      Various lubricating body fluids at tissue interfaces are composed mainly of combinations of phospholipids and amphipathic apoproteins. The challenge in producing synthetic replacements for them is not replacing the phospholipid, which is readily available in synthetic form, but replacing the apoprotein component, more specifically, its unique biophysical properties rather than its chemistry. The potential of amphiphilic reactive hypercoiling behaviour of poly(styrene-alt-maleic acid) (PSMA) was studied in combination with two diacylphosphatidylcholines (PC) of different chain lengths in aqueous solution. The surface properties of the mixtures were characterized by conventional Langmuir–Wilhelmy balance (surface pressure under compression) and the du Noüy tensiometer (surface tension of the non-compressed mixtures). Surface tension values and 31P-NMR demonstrated that self-assembly of polymer-phospholipid mixtures were pH and concentration-dependent. Finally, the particle size and zeta potential measurements of this self-assembly showed that it can form negatively charged nanosized structures that might find use as drug or lipids release systems on interfaces such as the tear film or lung interfacial layers. The structural reorganization was sensitive to the alkyl chain length of the PC.


      PubDate: 2015-07-05T15:51:57Z
       
  • Preparation and characterization of antimicrobial electrospun poly(vinyl
           alcohol) nanofibers containing benzyl triethylammonium chloride
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Jeong-Ann Park , Song-Bae Kim
      The aim of this study was to characterize antimicrobial electrospun poly(vinyl alcohol) (PVA) nanofibers containing benzyl triethylammonium chloride (BTEAC) as an antimicrobial agent. The antimicrobial BTEAC-PVA nanofibers were prepared through electrospinning at the optimal conditions of 15kV voltage and a 1.0mLh−1 flow rate. Based on the minimum inhibitory concentration (MIC) test results against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli and Klebsiella pneumonia, BTEAC-PVA nanofibers containing 2.6% BTEAC were fabricated to test the antibacterial and antiviral activities. The average diameter of the BTEAC-PVA nanofibers increased from 175.7 to 464.7nm with increasing BTEAC concentration from 0 to 2.6%. The antimicrobial activities of the BTEAC-PVA nanofibers were tested against bacteria. The antibacterial tests with 2.6% BTEAC-PVA nanofibers demonstrated that bacterial reduction in PVA nanofibers was similar to the control value, indicating that PVA had a minimal effect on bacteria death. For the BTEAC-PVA nanofibers, the bacterial reduction ratio increased with increasing contact time, demonstrating that BTEAC-PVA nanofibers successfully inhibited the growth of bacteria. In addition, the antiviral tests against viruses (bacteriophages MS2 and PhiX174) showed that the BTEAC-PVA nanofibers inactivated both MS2 and PhiX174.


      PubDate: 2015-07-01T15:44:36Z
       
  • Studies on uptake behavior of Hg(II) and Pb(II) by amine modified glycidyl
           methacrylate–styrene–N,N′-methylenebisacrylamide
           terpolymer
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Archana Gupta , Rajeev Jain , D.C. Gupta
      The removal of mercury and lead ions from aqueous solutions investigated by ethylenediamine, diethylenetriamine and tetraethylenepentamine functionalized polymeric adsorbent. The adsorbent was prepared by amination of terpolymer synthesized from glycidylmethacrylate, styrene and N,N′-methylenebisacrylamide. In the single metal species system (only mercury or lead ions are present) poly(glycidylmethacrylate–ethylenediamine) (PGMA–EDA), poly(glycidylmethacrylate–diethylenetriamine) (PGMA–DETA), and poly(glycidylmethacrylate–tetraethylenepentamine) (PGMA–TEPA) were found to adsorb lead or mercury ions with a slightly higher adsorption uptake capacity for lead than mercury ions. Among the three functionalized polymers poly(glycidylmethacrylate–diethylenetriamine) (PGMA–DETA) shows faster and higher adsorption capacity than poly(glycidylmethacrylate–ethylenediamine) (PGMA–EDA), poly(glycidylmethacrylate–tetraethylenepentamine) (PGMA–TEPA). The natural pH of both the metal ions was found to be most suitable for uptake. The uptake of Hg(II) and Pb(II) ions was investigated by using batch technique. The maximum adsorption capacities of Pb ions were predicted to be 4.74, 4.76 and 4.73mmol/g and the maximum Hg(II) ion uptakes were found to be 4.76, 4.80 and 4.21mmol/g respectively for PGMA–EDA, PGMA–DETA and PGMA–TEPA resins at their natural pH. The uptakes of Hg(II) and Pb(II) ions on the resins were found to follow Langmuir adsorption isotherm and pseudosecond order kinetics.


      PubDate: 2015-07-01T15:44:36Z
       
  • Synthesis of water-soluble wholly aromatic polyketones bearing
           1,1′-binaphthyl-6,6′-diyl units
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Katsuya Maeyama , Hiroaki Kumagai
      A water-soluble wholly aromatic polyketone modified with sodium carboxylate (PK-COONa) was synthesized through demethylation of the wholly aromatic polyketone bearing four methoxy groups per repeat unit (PK-OMe) followed by ethoxycarbonylmethylation and saponification. The obtained polyketones, i.e., the methyl-cleaved analogue (PK-OH), the ethoxy carbonyl group-bearing analogue (PK-COOEt), the sodium carboxylate analogue (PK-COONa), and the carboxy group-bearing analogue (PK-COOH), have varying solubilities in water and common organic solvents and thermal stabilities, depending on the functional groups.
      Graphical abstract image

      PubDate: 2015-07-01T15:44:36Z
       
  • Optically active, magnetic microspheres: Constructed by helical
           substituted polyacetylene with pendent prolineamide groups and applied as
           catalyst for Aldol reaction
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Jiexuan Song , Haiyang Zhang , Jianping Deng
      This article reports on the preparation of a novel category of optically active magnetic microspheres (OAMMPs) consisting of Fe3O4 nanoparticles and helical substituted polyacetylene bearing pendent prolineamide groups and the use of them for asymmetric direct Aldol reactions. The microspheres (200–300μm in diameter) were prepared by using chiral acetylenic monomer and alkynyl-Fe3O4 nanoparticles via suspension polymerization approach. They were obtained in high yield (>99%) with regular spheric morphology and exhibited noticeable optical activity, according to circular dichroism spectra and specific optical rotation measurements. The microspheres further served as chiral catalyst for performing direct Aldol reactions between acetone and p-nitrobenzaldehyde, providing the product in moderate yield (68%) and ee (75%). The magnetic microspheres can be easily recycled and reused. Mechanism for the asymmetric catalysis of Aldol reaction was further proposed.


      PubDate: 2015-07-01T15:44:36Z
       
  • Polymeric anion exchanger supported hydrated Zr(IV) oxide nanoparticles: A
           reusable hybrid sorbent for selective trace arsenic removal
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Surapol Padungthon , Michael German , Surases Wiriyathamcharoen , Arup K. SenGupta
      Natural groundwater contamination by arsenic puts over 100 million people at-risk throughout the world. If arsenic is the primary concern, the most ideal treatment solution would be a regenerable fixed-bed adsorbent: minimal energy requirement, simple operation and low cost. Such an adsorbent should have high arsenic capacity, high physical/chemical durability and high regenerability for several cycles of reuse. Hybrid anion exchange resins impregnated with hydrous zirconium oxide nanoparticles (HAIX–Zr) combine the physical durability and high anion diffusivity of anion exchanger resins with the high arsenic capacity and high chemical durability of zirconium oxides. HAIX–Zr was synthesized using non-hazardous and easy-to-transport pre-calcined zirconium oxide and was tested to be an effective As(V) and As(III) adsorbent over several cycles of exhaustion–regeneration in the presence of high concentrations of competing anions; at high concentrations, phosphate and silica show competition with arsenic. The high regenerability of HAIX–Zr (>90%) makes it more sustainable to regenerate and reuse the HAIX–Zr for numerous cycles to reduce the volume of arsenic-laden waste. Unlike other iron- or aluminum-based adsorbents, HAIX–Zr is chemically stable at landfill conditions where it could be safely disposed without leaching arsenic.


      PubDate: 2015-07-01T15:44:36Z
       
  • Tyramine modified alginates via periodate oxidation for peroxidase induced
           hydrogel formation and immobilization
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Olivera Prodanovic , Dragica Spasojevic , Milos Prokopijevic , Ksenija Radotic , Nevena Markovic , Marija Blazic , Radivoje Prodanovic
      Phenol and amino groups were introduced into alginate to different degrees via oxidation with 2.5, 5, 10, 15 and 20mol% of periodate and reductive amination by tyramine. Modification of alginate with tyramine was confirmed by FTIR spectroscopy and UV–VIS spectroscopy, while concentration of phenol and ionizable groups was determined using absorbance at 275nm and acid–base titration. All tyramine-alginates were able to form hydrogels after cross-linking with horse radish peroxidase (HRP) and hydrogen peroxide. Tyramine-alginates oxidized with up to 10mol% of periodate were also capable of forming hydrogels with calcium ions. Tyramine-alginates were tested for HRP immobilization within micro-beads obtained by peroxidase catalyzed droplet polymerization using internal delivery of hydrogen peroxide via glucose oxidase and glucose. Highest activity of immobilized peroxidase was obtained with 20% (w/v) tyramine-alginate obtained via 20mol% periodate oxidation. Immobilized enzyme was not leaking from the micro-beads and was further kinetically characterized for pyrogallol oxidation. Km for pyrogallol was increased after immobilization from 1.93mM for soluble HRP to 7.34mM for immobilized HRP. The optimum pH was also increased from pH7.0 to 8.0. Temperature and organic solvent stability improved significantly after immobilization, so that half-life at 70°C increased around four times, while half-life in 80% (v/v) dioxane increased 22 times. After repeated use of 6 times in batch reactor for pyrogallol oxidation immobilized HRP retained 45% of original activity.


      PubDate: 2015-07-01T15:44:36Z
       
  • pH-responsive superabsorbent polymers: A pathway to self-healing of mortar
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Arn Mignon , Didier Snoeck , David Schaubroeck , Nathalie Luickx , Peter Dubruel , Sandra Van Vlierberghe , Nele De Belie
      Cracks are concrete's worst problem. External, passive treatments are expensive and time consuming. pH-responsive superabsorbent polymers (SAPs) offer an internal active solution. When cracks occur, the SAPs can swell, fill the crack (self-sealing) and assist in the formation of healing products (self-healing). In previous work, a range of (superabsorbent) polymers have been synthesized and characterized. Based on these results, the two best performing SAPs were chosen for further characterization. The results indicate that the SAPs developed do not show degradation in cement filtrate solutions. Upon addition of SAPs, a decrease in mortar strength occurred, yet a positive effect on self-sealing was observed since the water permeability decreased. Furthermore, the formation of products became apparent at the sealed cracks of the mortar samples containing 1m% SAPs. Identification using scanning electron microscopy, infrared spectroscopy and thermogravimetric analysis indicated that the products mainly consisted of healing products (more specifically CaCO3) which is illustrative for self-healing.


      PubDate: 2015-07-01T15:44:36Z
       
  • Synthesis and characterization of poly(lactic acid) based graft copolymers
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Tungabidya Maharana , Sasmita Pattanaik , Anita Routaray , Nibedita Nath , Alekha Kumar Sutar
      This review summarizes recent developments in the preparation and characterization of grafting of poly(lactic acid) or polylactide (PLA). PLA is the most expansively researched and utilized biodegradable, biocompatible, compostable, recyclable and renewable thermoplastic polyester. The graft copolymers of PLA have been synthesized and characterized by different spectroscopic techniques, including FTIR spectra and NMR data. The graft copolymers of PLA have been analyzed critically by taking different monomers/polymers; such as chitosan, cellulose, starch, polyethylene glycol, vinyl based polymers, lignin, dextran, methyl methacrylate, maleic anhydride and graphene oxide. In the first part of this review, the grafting of PLA and applications of grafted PLA has been discussed briefly. The second part, the major objective of this paper, focuses on the synthesis and characterization of different PLA based graft copolymers. For few cases, where useful properties, such as high molecular weight, narrow PDI, or stereocontrol, have been observed, a more detailed examination of the graft copolymers is provided.


      PubDate: 2015-07-01T15:44:36Z
       
  • Facile method towards functionalization of partially fluorinated
           polyarylethers via sequential post-polymerization modification
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Jingbo Wu , Jau-Hung Liou , Charles Y. Shu , Yash Patel , Remya Menon , Cara Santucci , Scott T. Iacono , Dennis W. Smith Jr. , Bruce M. Novak
      A novel partially fluorinated arylene vinylene ether (FAVE) polymer containing ester groups was synthesized, which was used to prepare three reactive FAVE polymers containing carboxylic acid groups, alcohol groups, and acid chloride groups, respectively. Post-polymerization modifications of the FAVE polymer's carboxylic acid groups (via a DCC coupling procedure with the desired alcohol), alcohol groups (via DCC coupling or an acid chloride esterification procedure with the desired carboxylic acid or acid chloride), and acid chloride groups (via an optimized nucleophilic substitution reaction with the desired alcohol or amine) were successfully performed. Several examples have been successfully prepared to demonstrate the versatility of these developed modification methods. FAVE polymers have been prepared with NHS active ester groups, Disperse Red 1 chromophores, benzyl bromide groups, aryl trifluorovinyl ether groups, ATRP initiator groups, vinyl groups, propargyl groups, Disperse Orange 3 chromophores, and benzaldehyde groups. In most cases, analytical data are consistent with a quantitative conversion of the reactive or functional groups. It is demonstrated that no degradation of the FAVE polymer matrix occurs after multistep post-polymerization modification reactions.


      PubDate: 2015-07-01T15:44:36Z
       
  • Synthesis and evaluation of different adsorbents based on poly(methacrylic
           acid–trimethylolpropane trimethacrylate) and
           poly(vinylimidazole–trimethylolpropane trimethacrylate) for the
           adsorption of tebuthiuron from aqueous medium
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Raquel Justo da Fonseca , Mariana Gava Segatelli , Keyller Bastos Borges , César Ricardo Teixeira Tarley
      In the present study a new cross-linked copolymer poly(methacrylic acid–trimethylolpropane trimethacrylate) (named PMA) and poly(vinylimidazole–trimethylolpropane trimethacrylate) (named PVI) was synthesized through precipitation polymerization and applied to the adsorption of tebuthiuron. Adsorbent materials were characterized by using FT-IR, SEM, TGA, textural data, and elemental analysis. Kinetic study showed that the tebuthiuron adsorption was very quick and the equilibrium time was achieved at 20min for both polymers. Experimental kinetic data for both polymers were very well described by the second-order kinetic model, thus indicating that tebuthiuron adsorption involves chemical adsorption in different binding sites, which could control the reaction rate. Adsorption equilibrium data were better fitted to the dual-site Langmuir–Freundlich model, which recognizes the existence of two kinds of adsorption sites on the polymer surface ascribed to the presence of carboxyl and carbonyl groups from PMA and imidazole ring and carbonyl group from PVI. The maximum adsorption capacities of PMA and PVI were found to be 186.76 and 213.89mgg−1, respectively, which are much higher than other adsorbents.


      PubDate: 2015-07-01T15:44:36Z
       
  • Renewable epoxy networks by photoinitiated copolymerization of
           poly(3-hydroxyalkanoate)s and isosorbide derivatives
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): C. Lorenzini , D.L. Versace , E. Renard , V. Langlois
      New biodegradable epoxy networks derived from poly(3-hydroxyalkanoate)s and isosorbide were synthesized by photoinitiated cationic ring opening polymerization in the presence of diaryl iodonium salt (I 250). Bis-epoxidized terminated PHA oligomers, PHA-diepoxy, were first prepared in three steps, microwave assisted alcoholysis in the presence of ethylene glycol, condensation with allyl isocyanate and epoxidation of alkene terminal groups. Moreover, isosorbide diglycidyl ether (DGEDAS) was prepared by epoxidation of allylic derivative. The photoinitiated polymerization is a straightforward way applied at room temperature in a very short reaction time (i.e. 300s) to obtain renewable crosslinked networks that remain partially biodegradable by lipase. Higher degradability was observed by increasing the content of PHA.


      PubDate: 2015-07-01T15:44:36Z
       
  • New fluorescent hyperbranched polymeric sensors as probes for monitoring
           photopolymerization reactions
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Sandra Medel , Paula Bosch
      Two polychromophoric dansyl hyperbranched fluorescent probes (HBPs) have been used as fluorescent sensors to follow photopolymerization reactions of acrylic monomers through fluorescence monitoring. Simultaneously, photo-DSC measurements were conducted. The combined data obtained by both techniques allowed to measure precise and adequately the kinetics of the systems. Differences are found depending on the composition of the formulation, but no depending on the probe inserted in the systems. The behavior and sensitivity of the functional HBP's have been compared with their low molecular weight monochromophoric reference compounds. Hyperbranched polychromophoric probes showed the same sensitivity towards the process than the monochromophoric probes, confirming the high sensitivity of the hyperbranched probes. Also, the data obtained by fluorescence allow distinguishing the different steps involved in the mechanism of a radical crosslinking polymerization, which could not be observed only with calorimetric measurements. The advantages of the functional HBP fluorescent probes towards their low molecular weight homologues are discussed.
      Graphical abstract image

      PubDate: 2015-07-01T15:44:36Z
       
  • An investigation on the effect of phenylboronic acid on the
           processibilities and thermal properties of bis-benzoxazine resins
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Shujuan Wang , Qinxiang Jia , Yuhong Liu , Xinli Jing
      Benzoxazine resins (BZs) as a novel type of phenolic resin are high-performance matrix resin for advanced composites. Yet there still exist some deficiencies when used as ablative material in aerospace applications, such as high curing temperature and poor thermal stability. In the present study, the phenylboronic acid (PBA) modified BZs (PBBZs) exhibiting excellent processibilities and thermal properties were prepared by incorporating PBA into BZ. The viscosity, gel time and curing behaviors were examined to demonstrate that PBBZs possessed better processibilities than the BZ, representing the catalytic effect of PBA in this case. The incorporation of PBA accelerated the ring-opening polymerization of BZ, leading to the lower curing temperature. TGA results reveal that the cured PBBZs exhibit excellent thermal properties, where the char yield at 800°C (nitrogen atmosphere) reaches 63.7% and is increased by 14.1 percentage points than that of BZ. The formed phenylboronates during curing act as additional cross-linking points and increase the cross-linking density of the cured resin, which results in the enhancement of the glass transition temperature of BZ ranging from 165°C to 219°C. This study provides a new vision for the preparation of high-performance matrix resin for ablative materials by introducing aryl-boron backbone.
      Graphical abstract image

      PubDate: 2015-07-01T15:44:36Z
       
  • Aspartic acid in a new role: Synthesis and application of a pH-responsive
           cyclopolymer containing residues of the amino acid
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Zakariyah A. Jamiu , Hasan A. Al-Muallem , Shaikh A. Ali
      The reaction between diallylamine and dimethyl maleate afforded the Michael addition product dimethyl N,N-diallylaspartate [(CH2 CH–CH2)2NCH(CO2Me)CH2CO2Me] I , which upon treatment with dry HCl and ester hydrolysis with aqueous HCl gave its hydrochloride salt [(CH2 CH–CH2)2NH+CH(CO2Me)CH2CO2Me Cl−] II and N,N-diallylaspartic acid hydrochloride [(CH2 CH–CH2)2NH+CH(CO2H)CH2CO2H Cl−] III, respectively. The new monomers II and III underwent cyclopolymerization to give, respectively, cationic polyelectrolytes (CPEs) poly(II ) and poly(III). Under the influence of pH, triprotic acid (+) poly(III) was equilibrated to water-insoluble diprotic polyzwitterionic acid (±) IV, water-soluble monoprotic poly(zwitterion–anion) (± −) V, and its conjugate base polydianion (=) VI. The protonation constants of the carboxyl group and trivalent nitrogen in VI have been determined. A 20-ppm concentration of IV is effective in inhibiting the precipitation of CaSO4 from its supersaturated solution with an ≈100% scale inhibition efficiency for a duration of 50h at 40°C. The aqueous two-phase systems (ATPSs) of VI and polyoxyethylene have been studied. The transformation of water-soluble VI to insoluble IV makes it a recycling ATPS as it can be recycled by precipitation at a lower pH.


      PubDate: 2015-07-01T15:44:36Z
       
  • Synthesis and chemosensory properties of terpyridine-containing diblock
           polycarbazole through RAFT polymerization
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Ruey-Shin Juang , Po-Chih Yang , Hua-Wen Wen , Cheng-Yi Lin , Sih-Ciao Lee , Ting-Wei Chang
      This paper describes the synthesis of a terpyridine-containing diblock copolymer, poly(N-vinylcarbazole)-block-poly[4′-((4-vinylphenyl) phenyl)-2,2′:6′,2″- terpyridine] (poly(VK15-b-TPY4)), using the macro-chain transfer agent VK macro-CTA, and employing two-step reverse addition-fragmentation transfer (RAFT) polymerization. We examined the effect of terpyridine units on sensory characteristics of fluorescent chemosensors. VK macro-CTA and diblock copolymer poly(VK15-b-TPY4) both exhibited moderate thermal stability, with thermal decomposition temperatures of 5% weight losses at approximately 307°C and 378°C, respectively, suggesting that the enhancement of thermal stability was attributed to the incorporation of terpyridine segments into the block copolymer. Poly(VK15-b-TPY4) exhibited higher sensitivities to Ni2+ and Mn2+ ions, with Stern–Volmer constants (K sv) of 2.58×105 M−1 and 2.57×105 M−1, respectively. Adding a Zn2+ ion not only caused partial fluorescence enhancement (3.2-fold quantum efficiency) but also induced a bathochromic shift of emission peak by approximately 56nm (from 429nm to 485nm), indicating that the Zn2+-terpyridine complex reduced the twist and vibration of the C–C polymer backbone and enhanced the charge transfer from donors to acceptors because of the more planar and rigid structure. Our results suggest that poly(VK15-b-TPY4) is a promising material for chemosensory applications.


      PubDate: 2015-07-01T15:44:36Z
       
  • Applicability and toxicity evaluation of an adsorbent based on jujube for
           the removal of toxic heavy metals
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Byungryul An , Chang-Gu Lee , Mi-Kyung Song , Jae-Chun Ryu , Soonjae Lee , Seong-Jik Park , Dongye Zhao , Song-Bae Kim , Chanhyuk Park , Sang-Hyup Lee , Seok Won Hong , Jae-Woo Choi
      The removal of heavy metals from industrial wastewater is important, owing to its eco-toxicity in aqueous environment. In this study, the mechanism and efficiency of the removal of toxic heavy metals by an eco-friendly adsorbent was investigated. Various types of adsorbents made from jujube were synthesized by varying the drying temperature of gel-type beads and elution method for jujube constituents. The maximum adsorption capacity for lead and copper ions was determined using the Langmuir isotherm model, with DJB-A-S-F (freeze-dried jujube bead made from a solution of squeezed autoclaved jujube) having the highest values at 60.44mg/g (lead) and 20.33mg/g (copper). In addition, the characteristics of the various adsorbents were determined by the Brunauer–Emmett–Teller (BET) method, scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). Gas chromatography–mass spectrometry (GC–MS) was used to identify the constituents of DJB-A-S-F before and after adsorption of heavy metals (Pb- and Cu-DJB-A-S-F). Furthermore, in vitro cytotoxicity assay was performed to investigate whether the binding of heavy metals to DJB-A-S-F increases cellular toxicity. As a result, no differences in cell viability between DJB-A-S-F and the ones coupled to heavy metals were observed, indicating that the developed adsorbents are non-cytotoxic with good compatibility. Thus, DJB-A-S-F is a promising adsorbent for the removal of toxic heavy metal cations from wastewater.


      PubDate: 2015-07-01T15:44:36Z
       
  • Dynamic covalent cross-linked polymer gels through the reaction between
           side-chain β-keto ester and primary amine groups
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Binoy Maiti , Bhuban Ruidas , Priyadarsi De
      A dynamic covalent gel network was constructed via the coupling reaction between the pendant primary amine groups of poly(l-leucine methacryloyloxyethyl ester) (P(H2N-Leu-EMA)) and the side-chain β-keto ester functionalities of poly(2-(acetoacetoxy)ethyl methacrylate) (PAEMA) by varying the molar ratios of P(H2N-Leu-EMA)/PAEMA and the concentration of polymers in different solvents at room temperature. Fourier transform infrared (FT-IR) spectroscopy and solid-state 13C nuclear magnetic resonance (NMR) study confirmed the newly formed enamine bonds in the polymeric gel. Rheological studies showed that the mechanical strength of gels increased with increasing weight percentage (wt.%) of polymers in solution. Furthermore, polymer gels can be transferred to the mixture of starting polymer solutions by regulating the pH of the system, which can be further transformed into the gel state by adding an external base.
      Graphical abstract image

      PubDate: 2015-07-01T15:44:36Z
       
  • Photoprotective effect of starch/montmorillonite composites on
           ultraviolet-induced degradation of herbicides
    • Abstract: Publication date: August 2015
      Source:Reactive and Functional Polymers, Volume 93
      Author(s): Amanda S. Giroto , Adriana de Campos , Elaine I. Pereira , Tatiana S. Ribeiro , José M. Marconcini , Caue Ribeiro
      Despite the extensive research about polymer/clay composites and nanocomposites, there have been few investigations devoted to the resistance of these hybrids against ultraviolet radiation. This property is especially of interest for materials based on biodegradable polymers since they could be applied for slow release of light-degradable molecules, such as herbicides. This paper describes the photoprotective effect of starch/montmorillonite composites on the ultraviolet-induced degradation of ametryne, a commercial herbicide. The starch/montmorillonite composites highly loaded with ametryne (50% by weight), and different contents of clay were produced by the starch gelatinization method. The results showed that encapsulation of ametryne by starch/montmorillonite composites is simple and possible to be done as a one-step procedure. It was shown that the main photodegradation mechanism involves herbicide volatilization, which was significantly reduced due to formation of composites with starch and montmorillonite. The composite presented a synergistic photoprotective effect between components. 13C solid-state nuclear magnetic resonance (13C-NMR) and FTIR spectroscopy indicated that the photoprotective effect is based on absorption of ultraviolet radiation by starch/montmorillonite composites, and not due to herbicide interaction with the hybrid structure. The novel composites for controlled or slow delivery of herbicides exhibited a promising efficiency in protecting active inputs against solar light degradation in field.


      PubDate: 2015-07-01T15:44:36Z
       
  • Tunable release of silver nanoparticles from temperature-responsive
           polymer blends
    • Abstract: Publication date: Available online 19 June 2015
      Source:Reactive and Functional Polymers
      Author(s): R. Elashnikov , O. Lyutakov , Y. Kalachyova , A. Solovyev , V. Svorcik
      Polymer blends of thermoresponsive poly(N-isopropylacrylamide) and poly(methyl methacrylate) with in situ synthesized silver nanoparticles (AgNPs) are proposed as stimuli-responsive antimicrobial materials. AgNPs were prepared in the semi-dried polymer blends by N-methyl-2-pyrrolidone reduction. Temperature controlled kinetic of silver release was examined for different weight ratios of the polymers. Synthesized AgNPs were characterized by transmission electron microscopy and temperature-dependent releasing was analysed by ultraviolet–visible and atomic absorption spectroscopies. Temperature-dependent changes of polymer matrices were observed by confocal microscopy and infra-red spectroscopy. It was shown that the polymer weight ratio determines both, starting time and kinetic of nanoparticles release. Antibacterial activities of prepared material were demonstrated on gram-positive Staphylococcus aureus (S. aureus) and gram-negative Pseudomonas aeruginosa (P. aeruginosa). Quantitative evaluation of antimicrobial efficacy of prepared materials was performed on the base of inhibition zones size. It was shown that prepared materials could serve as effective antibacterial coating with quick antimicrobial response.


      PubDate: 2015-07-01T15:44:36Z
       
  • Editors and Editorial Board
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92




      PubDate: 2015-07-01T15:44:36Z
       
  • Extraction of chitosan from Aspergillus niger mycelium and synthesis of
           hydrogels for controlled release of betahistine
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Gustavo Muñoz , Carlos Valencia , Nora Valderruten , Eduardo Ruiz-Durántez , Fabio Zuluaga
      Chitosan was extracted from the fungus Aspergillus niger, an alternative source of chitin that is widely available as a byproduct of the industrial production of citric acid. Chitosan with deacetylation degree (DD) of 73.6% was characterized by elemental analysis, capillary viscometry (molecular weight of 1.9×105 g/mol), Fourier transform infrared (FTIR), nuclear magnetic resonance (1H NMR, 13C NMR and 15N NMR) spectroscopies, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Fungal chitosan was crosslinked with glutaraldehyde and glutaric acid to obtain hydrogels. Chitosan hydrogels were characterized by FTIR and by scanning electron microscopy (SEM), which showed that these materials have irregular, polydisperse, and interconnected pores. Kinetic studies of the release of betahistine from the swollen hydrogels showed a Fickian diffusion mechanism. Finally, hydrolytic degradation of chitosan hydrogels under simulated physiological conditions (pH 7.4 and 37°C) was investigated as well as in vivo biocompatibility tests using New Zealand white rabbits as animal models.


      PubDate: 2015-07-01T15:44:36Z
       
  • Adamantane-based epoxy resin and siloxane-modified adamantane-based epoxy
           resin: Characterization of thermal, dielectric and optical properties
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): C.W. Tsai , K.H. Wu , C.C. Yang , G.P. Wang
      An adamantane-based epoxy resin (ADEP) and a siloxane-modified adamantane-based epoxy resin (Siloxane-ADEP) were synthesized, and their chemical structures were confirmed from FT-IR, 1H, 13C and 29Si NMR spectroscopy measurements. The morphological, thermal, dielectric and optical properties of ADEP and Siloxane-ADEP were studied. The introduction of the adamantane group into the chain of the epoxy resin resulted in improvements in the thermal, mechanical and dielectric properties. These results can be explained in terms of the tricyclic hydrocarbon of the adamantane in a diamond lattice structure and the movement of polymer chains being limited by chair-form cyclohexane rings, resulting in an immobile epoxy structure. Moreover, Siloxane-ADEP exhibited good thermal, mechanical and dielectric properties that were similar to those of epoxy resin, and its better processability may extend its application to electronic packing materials. The UV–Vis transmission spectra revealed that the adamantane-containing epoxy membranes exhibited novel ultraviolet light-filtering properties.


      PubDate: 2015-07-01T15:44:36Z
       
  • PLGA/SF blend scaffolds modified with plasmid complexes for enhancing
           proliferation of endothelial cells
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Li Yu , Yakai Feng , Qian Li , Xuefang Hao , Wen Liu , Wei Zhou , Changcan Shi , Xiangkui Ren , Wencheng Zhang
      Biomimetic scaffolds have been investigated for vascular tissue engineering for many years. However, the design of an ideal biodegradable vascular scaffold is still in progress. The optimization of poly(lactide-co-glycolide)/silk fibroin (PLGA/SF) blend composition was performed to provide the designed scaffolds with adequate mechanical properties and favorable biocompatibility for the intended application. By systematically varying the weight ratio of PLGA and SF, we could control fiber diameter and hydrophilicity as well as mechanical properties of the fibrous scaffolds. These scaffolds with a weight ratio of PLGA/SF at 70/30 exhibited excellent performance, such as tensile strength of 1.5±0.1MPa, and elongation at break of 77.4±6.4%. Therefore, PLGA/SF scaffold with a weight ratio of 70/30 was chose as the matrix because it matches at best the mechanical demands for application in vascular tissue engineering. In order to promote the endothelialization of electrospun scaffolds, we used pEGFP-ZNF580 plasmid (pZNF580) complexes to modify the electrospun scaffolds by electrospraying technique. pZNF580 complexes were prepared from pZNF580 and microparticles (MPs) of amphiphilic copolymer methoxy-poly(ethylene glycol)-block-poly(3(S)-methyl-2,5-morpholinedione-co-glycolide)-graft-polyethyleneimine. Negatively charged PLGA/SF fibers adsorbed the positively charged MPs via physical deposition and electrostatic force. Scanning electron microscope image indicated the forming of composite scaffold and MPs did not change fiber’s shape and 3-D structure. Cell culture experiments demonstrated that the scaffolds modified with MPs/pZNF580 complexes could promote human umbilical vein endothelial cell growth and inhibit human umbilical artery smooth muscle cell proliferation. Our results indicated that the composite scaffolds with MPs/pZNF580 complexes could be used as a potential scaffold for vascular tissue engineering.


      PubDate: 2015-07-01T15:44:36Z
       
  • Refractive index changes in polyacrylates bearing alkyl sulfur groups
           through the sulfur oxidation reaction
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Jae Young Jang , Jung Yun Do
      Four polyacrylates with sulfur-containing side chains were prepared to examine the changes in refractive index (RI) induced by sulfur oxidation. Linear alkyl sulfides and alicyclic sulfides, such as 1,3-dithiolane and 1,4-dithiane, were introduced to impart large RIs to polyacrylates. Oxidation of the sulfur polymers by O3 and m-chloroperoxybenzoic acid led to the formation of the corresponding sulfoxide and sulfone polymers, respectively. Sulfur oxidation occurred completely, which was highlighted by the oxidized polymer exhibiting a refractive index comparable to a polymer that was synthesized using a sulfone monomer. The RI of the linear sulfur polymer increased and decreased due to the formation of sulfoxide and sulfone polymers, respectively. The Abbe number of the polymer with a linear sulfide side chain was 33.4, which increased to 48.7 after oxidation.


      PubDate: 2015-07-01T15:44:36Z
       
  • Exploring the post-polymerization modification of side-chain amino acid
           containing polymers via Michael addition reactions
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Amal Narayanan , Binoy Maiti , Priyadarsi De
      An efficacious protocol for the aza-Michael addition of a C-terminus modified phenylalanine side-chain containing polymer (Michael donor) was demonstrated with various Michael acceptors. The aza-Michael addition reactions were carried out at 50°C in anhydrous methanol, which is a protic solvent, to enhance the advancement of the reactions. 1H and inverse gated 13C NMR spectroscopy were utilized to qualitatively deliver comprehensive data on the reaction progress. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) provided quantitative information about the modification of the polymer. The extent of change in the aza-Michael addition varied with different Michael acceptors and decreased in the order of acrylate>acrylamide>methacrylate. The present study opens up a library of polymers with functional modifications in the side-chain.
      Graphical abstract image

      PubDate: 2015-07-01T15:44:36Z
       
  • Removal of Reactive Blue 21 onto magnetic chitosan microparticles
           functionalized with polyamidoamine dendrimers
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Peng Wang , Qianyun Ma , Dongying Hu , Lijuan Wang
      Chitosan/poly(amidoamine) (MCS/PAMAM) microparticles were prepared as magnetic adsorbents for removal of Reactive Blue 21 (RB 21) dye from aqueous solution. Characterization of these particles was carried out using scanning electron microscopy, Fourier transform-infrared spectroscopy, X-ray diffractometry and vibrating sample magnetometry. The results indicate that the magnetic chitosan microparticles (MCS) were functionalized with PAMAM dendrimers and maintained its intrinsic magnetic properties. The effects of initial pH, adsorbent dose, initial concentration, contact time and temperature on adsorption were investigated. Kinetic studies showed that the dye adsorption process followed a pseudo-second-order kinetic model but that the adsorption rate was also influenced by intraparticle diffusion. Equilibrium adsorption isotherm data indicated a good fit to the Langmuir isotherm. The maximum adsorption capacities obtained from the Langmuir model were 555.56, 588.24, 625.00 and 666.67mgg−1 at 303, 313, 323 and 333K, respectively. The thermodynamic parameters revealed the feasibility, spontaneity and endothermic nature of the adsorption. Recycling experiments confirmed the relative reusability of the adsorbent.


      PubDate: 2015-07-01T15:44:36Z
       
  • Selective removal of ATP degradation products from food matrices I: Design
           and characterization of a dummy molecularly imprinted specific sorbent for
           hypoxanthine
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Aurora Lasagabaster Latorre , Ma. Concepción Cela Pérez , Sara Fernández Fernández , J.M. López Vilariño , M.V. González Rodríguez
      Specific molecularly imprinted polymers (MIPs) for hypoxanthine (HYP) recognition in aqueous organic media have been developed based upon UV, FTIR and 1H NMR prepolymerization studies in conjunction with batch rebinding UPLC analyzes. The MIPs, which used the template mimics caffeine (CAF) and theophylline (TPH), are prepared in CHCl3 by one step precipitation polymerization from acrylamide (AM), 2-hydroxyethyl-methacrylate (HEMA) and methacrylic acid (MAA) as functional monomers, whereas ethylene glycol dimethacrylate (EGDMA), divinylbenzene (DVB) and trimethylolpropane triacrylate (TMPTA) as cross-linkers. The magnitude of the pre-polymerization binding constants between TPH and AM, MAA and HEMA is consistent with the complex stoichiometry (1:2 and 1:1) and number of interaction points (3-, 2-, 1-hydrogen bonded motif). The strong (1:2) complex between TPH and AM (K 11 =3.36×104 M−1 and K 12 =1.33×102 M−1) makes the corresponding MIP the most suitable for HYP recognition. The best performance of the TPH:AM:EGDMA (1:4:20) MIP is reflected in the high IF and high weighted average affinity based on the Freundlich isotherm. Further polymer characterization by ATR–FTIR, elemental analysis, surface area analysis (BET), swelling and SEM yield vital information regarding the degree of polymerization, real monomer:crosslinker ratio, morphology, pore size distribution plus conformational changes on exposure to different solvents.


      PubDate: 2015-07-01T15:44:36Z
       
  • Manufacture and performance of ethylamine hydroxyethyl chitosan/cellulose
           fiber in N-methylmorpholine-N-oxide system
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Xin Jin , Xiaofei Liu , Qianwen Liu , Yuan Li
      Ethylamine hydroxyethyl chitosan (EHC), a novel chitosan derivative which is soluble in aqueous N-methylmorpholine-N-oxide (NMMO) and antibacterial to Escherichia coli (E. coli) was synthesized. The structure, solubility and antibacterial capability of EHC were investigated. Results demonstrated the potential application for EHC in manufacture of antibacterial EHC/cellulose Lyocell fiber. Through environment-friendly Lyocell process in aqueous NMMO, the EHC/cellulose fiber was successfully fabricated and the various properties of EHC/cellulose fiber were studied. Results showed the EHC/cellulose fiber exhibited favorable consistency, antibacterial activity, mechanical properties and water retention compared with the fiber without EHC.


      PubDate: 2015-07-01T15:44:36Z
       
  • Antibacterial activity of chitosan grafting nisin: Preparation and
           characterization
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Xiaoming Zhu , Huan Wu , Jing Yang , Jun Tong , Jiayan Yi , Zhihai Hu , Jin Hu , Tan Wang , Lihong Fan
      Nisin grafted chitosan was prepared by using microbial transglutaminase as biocatalyst. The transglutaminase-catalyzed reaction displayed high efficiency, high selectivity, mild reaction condition and environmental friendliness. The results revealed that the degree of substitution (DS) of nisin–chitosan could be controlled by adjusting the reaction time, the reaction temperature and the molar ratio of nisin to chitosan. And nisin–chitosan in different pH showed excellent solubility. In addition, in vitro antibacterial activity assessment, nisin–chitosan with the concentration of 0.008mg/mL showed pronounced inhibitory effect against Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria (Escherichia coli). Furthermore, L929 mouse fibroblasts were cultured with nisin–chitosan, and the methylthiazol tetrazolium (MTT) assay showed that nisin–chitosan with the concentration from 0.005 to 0.01mg/mL displayed low toxicity. The results may contribute to finding the application of nisin–chitosan in pharmaceutical and food industry fields.


      PubDate: 2015-07-01T15:44:36Z
       
  • Preparation of monodispersed porous polyacrylamide microspheres via phase
           separation in microchannels
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Song Guo , Tong Yao , Chongqing Wang , Changfeng Zeng , Lixiong Zhang
      We report on the formation of polyacrylamide (PAM)/polyethylene glycol (PEG) core/shell droplets in a microchannel via the polymerization-induced phase separation of an acrylamide (AM)/PEG aqueous system. Monodispersed porous PAM microspheres were prepared from the PAM/PEG core/shell droplets, and we examined the effects of experimental parameters on the phase separation process and on the particle size and pore structure of the resulting PAM microspheres. PAM microspheres could be readily obtained with adjustable particle sizes and porosities by altering the PEG and crosslinker contents and by using PEG with different molecular weights. The relation between the swelling value and porosity is correlated.


      PubDate: 2015-07-01T15:44:36Z
       
  • Controlled synthesis of photosensitive graft copolymers with high
           azobenzene-chromophore loading densities in the main and side chains by
           combining ATRP and ADMET polymerization
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Liang Ding , Juan Li , Chengshuang Wang , Ling Lin
      Photosensitive graft copolymers containing azobenzene chromophores in the main and side chains were successfully synthesized by combining living atom transfer radical polymerization (ATRP) and acyclic diene metathesis (ADMET) chemistry based on the results of proper heterodifunctional inimer and azobenzene monomer design. The precise copolymer architectural features were manipulated by combining the macromonomer technique and the macroinitiator method. The as-prepared copolymer containing azobenzene chromophores in the main and side chains showed unique reversible isomerization processes, suggesting that the photoisomerization of azobenzene chromophores occured mainly in one of the two types of azobenzene groups in the main or side chains with similar probabilities due to their main and side-on structure.


      PubDate: 2015-07-01T15:44:36Z
       
  • Separation of americium from complex radioactive mixtures using a BTPhen
           extraction chromatography resin
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Matthew A. Higginson , Olivia J. Marsden , Paul Thompson , Francis R. Livens , Sarah L. Heath
      Extraction chromatography (EC) resins are widely used in analytical radiochemical separations, in particular for actinide separation. However, there is currently limited choice for separation of americium using EC, with DGA (N,N,N′,N′-tetra-n-octyldiglycolamide) resin being the preferred option. Here, we describe preparation and testing of a covalently-linked EC resin utilising a triazine soft N-donor (Me4BTPhen) extractant for americium extraction. The resin was generated by conjugation of a Me4BTPhen derivative with poly(vinylbenzyl) chloride to generate PVB–Me4BTPhen. PVB–Me4BTPhen was shown to extract americium from a complex matrix simulating nuclear forensic samples, and containing lanthanides, actinides and matrix elements with high Am (III) recovery (>90%) and low extraction of other elements, and provides an alternative to the currently used BTPhen liquid–liquid separation process for Am (III) extraction.


      PubDate: 2015-07-01T15:44:36Z
       
  • Immobilization of lecithin on bacterial cellulose nanofibers for improved
           biological functions
    • Abstract: Publication date: June–July 2015
      Source:Reactive and Functional Polymers, Volumes 91–92
      Author(s): Jing Zhang , Peng Chang , Chen Zhang , Guangyao Xiong , Honglin Luo , Yong Zhu , Kaijing Ren , Fanglian Yao , Yizao Wan
      In an attempt to improve the biological behavior of pristine bacterial cellulose (BC), lecithin (LEC) has been immobilized on the surface of BC nanofibers by solution immersion and subsequent chemical crosslinking with proanthocyanidin (PA). The as-prepared LEC-immobilized BCs (denoted as BC/LECs) were characterized by SEM, FTIR, and XRD, and their dynamic mechanical properties, thermal stability, and hydrophilicity were assessed. The presence of LEC on BC surface was confirmed by SEM and FTIR analyses. It has been found that BC/LECs retain the three-dimensional (3D) porous network structure of pristine BC. The BC/LECs still demonstrate favorable mechanical properties, surface hydrophilicity, and thermal stability. More importantly, preliminary cell studies suggest that the BC/LECs show improved cell behavior over pristine BC.


      PubDate: 2015-07-01T15:44:36Z
       
  • Poly(dopamine)-assisted preparation of star poly(ethylene glycol)-based
           coatings: A detailed study of their protein resistance and application in
           CE
    • Abstract: Publication date: Available online 28 May 2015
      Source:Reactive and Functional Polymers
      Author(s): Chong Zhang , Lijuan Chen , Lin Tan , Xiajun Zheng , Yanmei Wang
      In this study, a set of well-defined multiarm star copolymers, hyperbranched poly(ethylenimine)-graft-poly(ethylene glycol) (bPEI-g-PEG) with different PEG grafting ratios were synthesized. The star PEG-based coatings were then prepared by immobilizing the corresponding copolymers onto poly(dopamine) (PDA)-coated substrates. The chemical composition, hydrophilicity, surface topography, and thickness of the coatings were studied by X-ray photoelectron spectroscopy (XPS), water contact angle (WCA), atomic force microscopy (AFM), and variable angle spectroscopic ellipsometry (VASE), respectively. Furthermore, the surface PEG chain density of star PEG-based coating was evaluated quantitatively and compared with that of linear PEG-based coating. Our results showed that the amount of proteins (albumin from bovine serum, fibrinogen, and lysozyme) adsorbed on the star PEG-based coating as measured by surface plasmon resonance (SPR) was found to be dependent on the surface PEG chain density, which was controlled by the polymer incubation concentrations and PEG grafting ratios. Generally, the star-shaped PEG gave the surface with higher PEG chain density than linear ones and the amount of adsorbed proteins decreased with increasing surface PEG chain density. At last, the star PEG-based coating was successfully applied into the capillary inner surface for protein separation by capillary electrophoresis (CE).


      PubDate: 2015-07-01T15:44:36Z
       
  • Efficacy of different generations and concentrations of PAMAM–NH2 on
           the performance and structure of TFC membranes
    • Abstract: Publication date: Available online 22 May 2015
      Source:Reactive and Functional Polymers
      Author(s): Yaghoub Mansourpanah , Zeinab Jafari
      In this work, several polyamide thin layer membranes were prepared and modified with polyamidoamine (PAMAM) dendrimers in different generations (G 0, G 1, and G 2) and different concentrations (0.5, 1.5 and 3wt.%) to investigate the occurring changes in the performance and morphology of the prepared thin layers. SEM and AFM data (reinforced with SPM software) proved that the dense and compressed surfaces were fabricated by loading and increasing of the generations and concentrations of PAMAM. In addition, the MWCO of the membranes drastically decreased. The chemical properties of the surface were investigated with ATR-IR and the occurring changes were studied. The zeta potential measurements illustrated that the surface charge of the thin layers was changed with alteration in the generations and concentrations of PAMAM. Additionally, in some cases the rejection capability of NaCl increased over 90%. Furthermore, the contact angle results clearly demonstrated an enhancement in the hydrophilicity of the membranes. The flux recovery ratio of the thin layers increased from 63% (in the unmodified thin layer) to near 97% in the thin layer composed of 3wt.% G 0.


      PubDate: 2015-07-01T15:44:36Z
       
  • Editors and Editorial Board
    • Abstract: Publication date: May 2015
      Source:Reactive and Functional Polymers, Volume 90




      PubDate: 2015-07-01T15:44:36Z
       
  • Challenging activated monomer ring-opening polymerization for direct
           synthesis of thiol end-functionalized polyesters
    • Abstract: Publication date: May 2015
      Source:Reactive and Functional Polymers, Volume 90
      Author(s): Maksym A. Kryuchkov , Ying Hua Qi , Iryna I. Perepichka , Carole Pelletier , Aurelie Regnaud , Zhengji Song , Sunil K. Varshney
      A direct, non-enzymatic procedure for the synthesis of thiol-functionalized polylactones was developed and optimized by using 2-mercaptoethanol, the simplest unprotected thiol-containing initiator for cationic ring-opening polymerization, catalyzed by HCl and methanesulfonic acid in dichloromethane solutions. Thiol-functionalized polylactones with a molecular weight of up to approximately 5000Da were obtained in a controlled manner. It was observed that acid can play the dual role of activator and initiator, and for the first time, it was shown that abundant HCl and/or ambient temperature lead to the formation of undesired α-carboxy-ω-chloro-functionalized polylactones that form in parallel with the targeted thiol-functionalized ones. A plausible pathway towards the formation of chlorinated products is proposed based on an active-chain-end mechanism, and the procedure was optimized to eliminate its contribution to the polymerization process, thus allowing for the activated-monomer mechanism to prevail. Molecular weight characterization was performed using 1H NMR and size-exclusion chromatography. The results indicate that the polymers obtained under optimized conditions possess high SH functionality and moderate polydispersity, and that ring-opening polymerization proceeded in a controlled fashion. The proposed method allows for the preparation of metal free materials readily suitable for biomedical and/or electronic applications.


      PubDate: 2015-07-01T15:44:36Z
       
  • Synthesis of conjugated polymers bearing pendant bipyridine ruthenium
           complexes
    • Abstract: Publication date: May 2015
      Source:Reactive and Functional Polymers, Volume 90
      Author(s): Yuxia Jin , Yingliang Liu , Wenbo Wu , Qiong Wu , Hongyan Gao , Chenxu Wang , Shengang Xu , Shaokui Cao
      Conjugated polymers bearing pendant bipyridine groups, PM1PT-x, were synthesized in high yield from a carefully designed dibromocarbazole monomer M1 using a Suzuki coupling reaction with a phenothiazine diborate monomer. PM1PT-x, where x is the mole percentage of M1 in the total feed of dibromo-monomers and varied to levels of 25%, 50%, 75% and 100%, was reacted with a ruthenium complex to yield conjugated polymers bearing pendant bipyridine ruthenium complexes, PM1PT-x-Ru. The introduction of ruthenium complexes extended the absorption of PM1PT-x-Ru to the visible light region. Furthermore, these polymers demonstrated sufficient stability and suitable energy levels to potentially be highly efficient photoactive materials for polymeric solar cells.


      PubDate: 2015-07-01T15:44:36Z
       
  • The potential of Kraft black liquor to produce bio-based
           emulsion-templated porous materials
    • Abstract: Publication date: May 2015
      Source:Reactive and Functional Polymers, Volume 90
      Author(s): Amandine Foulet , Marc Birot , Guido Sonnemann , Hervé Deleuze
      Emulsion-templated porous monoliths based on castor oil-in-black liquor and on 1,2-dichloroethane-in-black liquor medium internal phase emulsions have been prepared in order to evaluate a possible valorisation of that undervalued by-product of the paper mill Kraft process. The cross-linking behaviour of the different polymers originally contained in the black liquor was investigated. It appears that both lignin and hemicellulose fragments are involved. Characterisation of the monoliths by scanning electronic microscopy and mercury intrusion porosimetry showed that using either castor oil or 1,2-dichloroethane allowed to obtain macrocellular morphology along with a high porosity. However, higher concentration of the internal phase is possible in emulsions prepared with 1,2-dichloroethane than with castor oil, leading to more attractive materials from both chemical and environmental aspects.


      PubDate: 2015-07-01T15:44:36Z
       
  • Cross-linking of cellulose and poly(ethylene glycol) with citric acid
    • Abstract: Publication date: May 2015
      Source:Reactive and Functional Polymers, Volume 90
      Author(s): Pamela de Cuadro , Tiina Belt , Katri S. Kontturi , Mehedi Reza , Eero Kontturi , Tapani Vuorinen , Mark Hughes
      A novel approach to modifying native cellulosic fibres with poly(ethylene glycol) (PEG) impregnation and simultaneous cross-linking by citric acid (CA) was investigated. To understand the contributions of different components in the system, control references with just CA and cellulosic fibres (filter paper) were studied. The effect of sodium hypophosphite as a catalyst was also assessed. The results revealed that ester bonds are indeed formed in the cellulose–PEG–CA reaction system, as indicated by weight percentage gain (WPG) and FTIR analysis. The best results were achieved by using 5% CA and 10% PEG (calculated as weight-% from cellulose). In the reaction, the environmentally friendly CA prevents PEG from being leached out of cellulose during washing, resulting in promising future applications in dimensionally stabilized products based on cellulosic fibres.


      PubDate: 2015-07-01T15:44:36Z
       
  • Stimuli responsive carbon nanocomposite hydrogels with efficient
           conducting properties as a precursor to bioelectronics
    • Abstract: Publication date: May 2015
      Source:Reactive and Functional Polymers, Volume 90
      Author(s): Priyanka Dutta , Narendra Nath Dass , Neelotpal Sen Sarma
      Stimuli responsive conducting carbon nanocomposite hydrogels were synthesized from glycerol methacrylate, ethylene glycol methacrylate and diethylene glycol methacrylate by thermal polymerization techniques. Carbon nanoparticles of size <50nm were incorporated into the polymer at a concentration of 0.005% (w/w) during synthesis. The hydrogels were characterized by Fourier Transform-Infrared Spectroscopy, thermogravimetric analysis, Scanning Electron Microscopy techniques and X-ray diffraction study. The hydrogels have excellent absorption properties in aqueous solvents which is sensitive to pH, temperature, ionic strength, etc. For instance, the pH sensitive swelling behavior of Polyglycerylmethacrylate-carbon nanocomposite increases from acidic medium (SR∼24, pH=3) to basic medium (SR∼130, pH=12). The hydrogels also showed significant swelling behavior in presence of different biological samples such as folic acid, uric acid, DNA and RNA. The electrical impedance value decreases to a large extent after the addition of carbon nanoparticles into the gels. It was observed that the conductivity rises to a maximum of about 1000 folds in the nanocomposite hydrogels. The increase in electrical conductivity is also verified by current–voltage measurements.


      PubDate: 2015-07-01T15:44:36Z
       
  • Influence of solvent characteristics in triaxial electrospun fiber
           formation
    • Abstract: Publication date: May 2015
      Source:Reactive and Functional Polymers, Volume 90
      Author(s): Abdurizzagh Khalf , Kumar Singarapu , Sundararajan V. Madihally
      Triaxial electrospinning is a novel method for fabrication of multilayered nano and microsize fibers with desirable features for particular applications. Since the effect of solvent volatilities in each layer and relative polymer molecular weights on uniform encapsulation of the core polymer process is not well understood, we evaluated (i) the role of solvent volatilities, and (ii) molecular weights using cellulose acetate (CA, 30kDa), polycaprolactone (PCL, 45kDa and 80kDa), mineral oil, and polyvinyl alcohol (PVA, 30kDa and 100kDa). Different solvent mixtures were evaluated based on the boiling points determined using a simulator. Inner mineral oil was selectively removed to form Hollow fibers. Analysis of chemical compositions using FT-IR and DSC revealed the presence of each component. 24-h viability of human umbilical vein endothelial cells indicated the formed fibers were not toxic. Scanning electron micrographs indicated the formation of triaxial structured fiber of outer hydrophobic PCL/CA/Hollow, PCL/PVA/Hollow and outer hydrophilic CA/PCL/Hollow fibers. Tensile tests (both wet and dry) revealed that PCL/CA/Hollow fibers had increased stiffness and load carrying capacity than CA/PCL/Hollow fibers. Successful fiber formation was dependent on ensuring that the outer shell formed first i.e., the relative solvent volatility of encapsulating core polymer to lower than that of the shell polymer.


      PubDate: 2015-07-01T15:44:36Z
       
  • Editors and Editorial Board
    • Abstract: Publication date: April 2015
      Source:Reactive and Functional Polymers, Volume 89




      PubDate: 2015-07-01T15:44:36Z
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2015